Since green is a color of Christmas, the spirit of the holiday season is frequently expressed through living plants.Indoor garderners, who enjoy green plants the year round and use them to enhance their surroundings should have little trouble including the plants in Christmas decorating.

At Christmastime, indoor plants, especially foliage plants, can become an integral part of the seasonal decorations, with or without added touches of tinsel and trinkets.

The Norfolk Island Pine can be your perennial Christmas tree. (Suggestions for trimming were given in another column.)

Other indoor plants can be incorporated in your decorating.

It is practically and aesthetically inadvisable to burden plants with ornaments that may damage plants or compete with their natural beauty. But some lightweight and small-scale ornaments may be added effectively.

Set lengths of flexible, silvery wire, such as that available in craft shops, in the soil around your spider plant and attach tiny, colorful baubles at the end of the wires. Voila! A fountain of color when the baubles are set in motion above the plant.

String miniature lights - clear or colored - in the branches of Ficus benjamina. Add a colorful 3-inch glass bird or two. Handsome ones, made in Czechoslovakia, are available locally. The birds are fashioned with clamps for easy attachments to branches.

Trim a jade plant. I'm trying a gilded Czechoslovakian peacock with bows of gilt cord, but may decide that my Kabuki dolls or other Japanese mementoes are more in keeping with the bonsai planting.

Slip branches of holly or sprigs of mistletoe in to a grouping of foliage plants on a mantel or low table. A red velvet bow attached to a plant stake in Boston fern or dieffenbachia will add a festive touch.

On a shelf of a room divider, trail oa vining pothos around a non-drip candle with a sprig of holly.

Use several small pots of ivy enlivened with holly as a centerpiece for dinner or party table.

Arrange small specimens of peperomia, table ferns, ivy, philodendron or pothos as background for tabletop nativity scene.

Even a palm can be brought into the picture by trimming it with bows, tinsel or with restraint, some shiny ornaments. Many palms produce large bunches of orange seeds; perhaps you can find a way to use bittersweet berries or orange pyracantha berries to give a fruitful appearance.

Decorating and other activities of the season may require moving plants from their accustomed places. Such changes may alter light, temperature and humidity conditions. The indoor gardener should be alert to possible effects in changing environments and should return plants to their preferred locations as soon as possible.

And a word of caution. Be careful of investing in a living Christmas tree in a nursery container or pot. It is very difficult tokeep a living Christmas tree (which is an outdoor plant) in the house during the holiday season in sufficiently good condition for it to survive outdoor planting after Christmas.